Is Castro Valley, CA tap water safe?

A town can be served by more than one utility, and some homes are on private wells. The name on your water bill tells you which is yours, and your ZIP code narrows it down. They are listed by how many people each serves in Castro Valley’s ZIP codes, from EPA’s estimates.

• East Bay MUD

  California · serves 1.5 million people · about 37,500 in Castro Valley

  1 result above the health goal. The worst: Uranium at 5.3 ppb, above the health goal. Hardness: soft to moderately hard depending on the source, 17 to 120 mg/L (1 to 7 grains per gallon).

  No health-based violations since 2016

  Open report

• Norris Canyon Property Owners Assn

  California · serves 50 people · under 100 in Castro Valley

  Nothing in its records is above a health goal. Hardness: very hard, 241 mg/L (14.1 grains per gallon).

  1 health-based violation since 2016

  Open report

MUD stands for municipal utility district, a local water and sewer district common in Texas.

Which ZIP codes are in Castro Valley: Census 2020 relationship files. Which utilities serve them, and how many people: EPA SDWIS and EPA’s service area map. Each utility’s results: EPA UCMR 5, EPA SDWIS, and EPA’s and the state’s compliance monitoring, as its report lists them. How they are measured: methodology. Certified labs: California State Water Resources Control Board, ELAP accredited laboratories and their fields of accreditation; distances from the Census 2020 ZIP code tabulation area gazetteer.